Joint for a metal airplane skin using metal matrix composite

ABSTRACT

A joint for a metallic skin structure includes a first end portion of the metallic skin structure and a second end portion of the metallic skin structure, wherein the first end portion and the second end portion of the metallic skin structure are secured together along a line of securement. The joint further includes at least one reinforcing fiber embedded within at least one of the first end portion of the metallic skin structure or the second end portion of the metallic skin structure extends orthogonal relative to the line of securement.

FIELD

This disclosure relates to an airplane having a metallic skin structure and more particularly to strategically reinforcing a joint in the metallic skin structure to reduce migration of fatigue cracking in the metallic skin structure.

BACKGROUND

Aircraft constructed of a metal skin have joints in the metallic skin structure such as lap joints which have overlapping portions of the metallic skin structure connected together with fasteners such as rivets. Fatigue cracking at the fastener head location in the lap joint can occur as a result of the operation of the aircraft such as for example occurring in a fuselage metallic skin structure in response to tensile stress from hoop tension load experienced at a head location of the fastener. This can result in cracking within the metallic skin structure in a direction along the line of securement of a row of fasteners such as rivets.

Fatigue cracking can also occur as a result of errors introduced in the process of fabricating the lap joint causing cracks to extend between fastener securements in the metallic skin structure. The fatigue cracks can originate in the metallic skin structure as a result of fastener counter sinks which have been placed too deep and from double drilled holes both of which can reduce fatigue life of the lap joint.

Current lap joints splice constructions provide reliable construction connections such as with using three or four rows of connections within the lap joint. Utilizing four rows of connections has improved the lap joint performance. However this construction does not eliminate the sensitivity to manufacturing errors which can introduce fatigue cracking within the metallic skin structure. There is a need when fatigue cracking occurs in this joint to reinforce the metallic skin structure so as to mitigate fatigue crack progression within the metallic skin structure.

Another example of a joint within a metallic skin structure includes use of a weld to secure together ends of portions of the metallic skin structure. Generally the weld is weaker than the metallic skin structure. However, in the process of welding the metallic skin structure weakens adjacent to the weld in what is referred to as the heat affected zone. The metallic skin structure positioned within the heat affected zone is a likely area in which fatigue cracking will occur within the metallic skin structure. As a result there is a need when fatigue cracking occurs in this joint to reinforce the metallic skin structure so as to mitigate fatigue crack progression within the metallic skin structure.

Even though fatigue cracking can be expected within the metallic skin structure with the metallic skin structure being safe to operate there is a need to mitigate the progression of the fatigue cracking so as to provide an enhanced margin of safety with respect to the metallic skin structure. This is the case regardless of whether the cracking within the metallic skin structure at a joint in a metallic skin structure was introduced by operation of the aircraft or by way of an error in the manufacturing process or otherwise. The mitigation is needed to prevent the cracking from progressing, for example, to an adjacent fastener opening in the case of a lap joint resulting and making lap joints less sensitive to manufacturing errors. There is also a need to mitigate the progression of any fatigue cracking within the metallic skin structure along a weld joining two ends of different portions of metallic skin structure in furtherance of enhancing the margin of safety of this joint as well. In the effort of mitigating the progression of fatigue cracking it would be beneficial to avoid unnecessary increases in the weight of the aircraft. Such mitigation should provide for increased structural fatigue life of the joint and provide for a reduction of structural inspections, all of which would save costs in operation and maintenance of the aircraft.

SUMMARY

An example includes a joint for a metallic skin structure includes a first end portion of the metallic skin structure and a second end portion of the metallic skin structure, wherein the first end portion and the second end portion of the metallic skin structure are secured together along a line of securement. The joint further includes at least one of a reinforcing fiber embedded within at least one of the first end portion of the metallic skin structure or the second end portion of the metallic skin structure extends orthogonal relative to the line of securement.

An example includes a method for fabricating a joint for a metallic skin structure, which includes the steps of securing a first end portion of the metallic skin structure to a second end portion of the metallic skin structure along a line of securement. The method further includes positioning at least one reinforcing fiber embedded within at least one of the first end portion or the second end portion, wherein the at least one reinforcing fiber extends orthogonal relative to the line of securement.

The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.

BRIEF SUMMARY OF THE DRAWINGS

FIG. 1 is a perspective view of an aircraft utilizing a metallic skin structure;

FIG. 2A is a partial perspective view of a first example of a joint for a metallic skin structure which includes a weld joining a first end portion and a second end portion of the metallic skin structure of the aircraft in FIG. 1, with fatigue cracks positioned within the metallic skin structure;

FIG. 2B is a partial perspective view of a second example of a joint for a metallic skin structure which includes an overlap of a first end portion and a second end portion of a metallic skin structure of the aircraft in FIG. 1 with rows of aligned bores which extend through the first and second end portions for positioning fasteners there through (not shown) for securement and fatigue cracks positioned within the metallic skin structure;

FIG. 3 is a partial perspective view of embedding reinforcing fibers with an ultrasonic horn into metallic skin structure used in constructing a joint for the metallic skin structure of the aircraft of FIG. 1;

FIG. 4 is a partial perspective view of the first example of the metallic skin structure joint of FIG. 2A, showing metallic fibers having been embedded into first end portion of the metallic skin structure, the weld and the second end portion of the metallic skin structure;

FIG. 5 is a partial perspective view of the cross section taken along line 5-5 as seen in FIG. 4;

FIG. 6 is an exploded view of the second example of the overlap joint of FIG. 2B additionally with representative reinforcing fibers shown which have been embedded in the first end and second end portions of the metallic skin structure;

FIG. 7 is an enlarged partial perspective assembled view of what is encircled and designated as 7 in FIG. 6;

FIG. 8A is a cross section view taken along line 8A-8A in FIG. 7 with a representative fastener positioned extending through a first bore of first plurality of bores positioned in the first end portion of the metallic skin structure and a first bore of the second plurality of bores positioned in the second end portion of the metallic skin structure;

FIG. 8B is a cross section view taken along line 8B-8B in FIG. 7 with a representative fastener positioned extending through the first bore of the first plurality of bores in the first end portion of the metallic skin structure and the first bore of the second plurality of bores in the second end portion of the metallic skin structure;

FIG. 9 is an enlarged view of what is encircled and designated 9 in FIG. 6 showing reinforcing fibers positioned within the first and second end portions of the metallic skin structure; and

FIG. 10 is a flow chart of a method for fabricating a joint for a metallic skin structure.

DESCRIPTION

As mentioned earlier, aircraft 10 as seen in FIG. 1, has a metallic skin structure, which is constructed of aluminum or other known metal(s) used in fabricating aircraft 10, such as for fuselage 12, wings 14 as well as other locations in aircraft 10. Metallic skin structure have end portions of the metallic skin structure which are secured together at a joint which can have different construction configurations. These joints can include, for example, joint 16, as seen in FIG. 2A, which joins together first end portion 18 of metallic skin structure and second end portion 20 of metallic skin structure, wherein first end portion 18 and second end portion 20 are secured together with weld 22. Another joint 16′ is shown in FIG. 2B wherein first end portion 18 is positioned in overlying relationship to second end portion 20 forming an overlap and first and second end portions 18, 20 are joined or secured together along with rows of fasteners (not shown) which are positioned within the rows of bores shown in FIG. 2B. Fasteners (not shown) in FIG. 2B can be, for example, rivets 24 as shown for example in FIGS. 8A, 8B.

Fatigue cracks 26, as shown in FIG. 2A, are positioned in first and second end portions 18, 20 of metallic skin structure on either side of weld 22. As mentioned earlier, fatigue cracks can occur within the metallic skin structure positioned within the heat affected zone adjacent to weld 22 wherein for example tensile force experienced in joint 16 can commence fatigue cracks, such as fatigue cracks 26, and cause them to propagate within the metallic skin material of first and second end portions 18, 20 along a line of securement of joint 16, along weld 22, which will be discussed in more detail herein.

In overlap joint 16′, as seen in FIG. 2B, one or both of first and second end portions 18, 20 are positioned in overlying relationship to one another can experience fatigue cracks 28 which extend from one or more bores which receive fasteners for securing the first and second end portions 18, 20 together. Fatigue cracks 28 occur for one or more reasons earlier discussed which include tensile forces exerted on joint 16′ from operation of aircraft 10 and as a result of errors introduced in the process of fabricating joint 16′. Manufacturing errors may be introduced during the fabrication process such as with fastener counter sinks which have been placed too deep and such as with double drilled holes which both contribute to reduced fatigue life at overlap joint 16′. Fatigue cracks 28, as seen in FIG. 2B, occur in the metallic skin structure and extend along a line of securement such as a row of fasteners which will be discussed in more detail herein.

Current overlap joint 16′ splice constructions provide reliable construction connections. The use of four rows of fasteners, as mentioned earlier, in lap joint 16′ has improved lap joint 16′ performance. However this construction and securement has not eliminated the sensitivity to manufacturing errors which can introduce cracking within the metallic skin structure wherein those cracks within the metallic skin structure can extend and progress within the metallic skin structure.

As mentioned earlier, joints 16 and 16′are designed for safe operation however there is a need to enhance the margin of safety for metallic skin structures with the mitigation of the extension and progression of any fatigue cracking within the metallic skin structures at a joint 16 which has been welded or in the case of lap joint 16′ which has been for example riveted together. The mitigation would provide for increased structural fatigue life and provide for a reduction of structural inspections. As mentioned earlier, there is also a need to avoid experiencing unnecessary increases in the weight of the aircraft in mitigating crack extension and progression.

As seen in FIG. 3, reinforcing fibers 30 are shown being embedded into first end portion 18 of metallic skin structure which will similarly be embedded into second end portion 20 (not shown) in constructing joint 16 and lap joint 16′. Reinforcing fibers 30 can be constructed of metallic or nonmetallic material and are made from very strong materials which are stronger than the aluminum or similar metals from which the metallic skin structure is constructed. Some materials selected for use for fiber 30 include aramid, ceramic or silicon carbide fibers and other such strong materials. As will be discussed in more detail herein, reinforcing fibers 30 will be embedded within first and second end portions 18, 20, and weld 22 for joint 16 as seen in FIGS. 4 and 5 and will be embedded within first and second end portions 18, 20 for lap joint 16′ as seen in FIGS. 6-9. The embedding of reinforcing fibers 30, as will be discussed, strengthen the joint and will inhibit growth of fatigue cracks 26 and 28 within the metallic skin structure.

Reinforcing fibers 30, in this example, can be used in a range of diameters including fifty ten thousandths of an inch to up to and including sixty ten thousandths of an inch (0.0050-0.0060 inches). Reinforcing fibers 30 are embedded into the metallic skin structure at a depth distance from the surface of first and second end portions 18, 20 and weld 22 of at least one thousandth of an inch (0.001 inch). The embedding is accomplished in this example with using an ultrasonic horn 32. Ultrasonic horn 32 is pressed against reinforcement fiber 30 and the metallic skin structure and the vibrations from ultrasonic horn 32 press reinforcement fiber 30 into the metallic skin structure. This embedding process is employed, in this example, at a temperature of approximately three hundred degrees Fahrenheit (300° F.).

A first example of joint 16 is shown in FIGS. 4 and 5 wherein joint 16 includes first end portion 18 of metallic skin structure of aircraft 10 and second end portion 20 of metallic skin structure of aircraft 10. First and second end portions 18, 20 are secured together along a line of securement L, in this example, with weld 22. Additionally, joint 16 includes at least one reinforcing fiber 30 embedded within at least one of the first end portion 18 or the second end portion 20 and extends orthogonal to the line of securement L. The arrangement of reinforcing fibers 30 will be discussed below in further detail for first example of joint 16.

As seen in FIG. 5, first end portion 18 includes first end 34 and second end portion 20 includes second end 36. First and second ends 34, 36 are positioned aligned and facing each other. First end 34 and second end 36 are secured together with weld 22 positioned between first end 34 and second end 36. Weld 22 can be any one of a variety of welds such as a conventional weld, a friction stir weld or other commonly known welds. Weld 22 extends along first end 34 and second end 36. Weld 22, as seen in FIG. 5, defines line of securement L.

At least one reinforcing fiber 30 is embedded within first end portion 18 positioned on first side 38 of line of securement L. At least one reinforcing fiber 30 extends from first end portion 18 and into and embedded within weld 22. At least one reinforcing fiber 30 extends from weld 22 into and embedded within second end portion 20 of the metallic skin structure positioned on an opposing second side 40 of line of securement L.

In referring to FIG. 5, the at least one reinforcing fiber 30 includes a first plurality 42 of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within first plurality 42 of reinforcing fibers 30 extend spaced apart from one another. The first plurality 42 of reinforcing fibers 30 are embedded within the first end portion 18 on first side 38 of line of securement L and extend through first end portion 18 positioned closer to first surface 44 of first end portion 18 than to opposing second surface 46 of first end portion 18. First plurality 42 of reinforcing fibers 30 extend from first end portion 18 and into and embedded within weld 22 positioned closer to first surface 48 of weld 22 than to opposing second surface 50 of weld 22. The first plurality 42 of reinforcing fibers 30 extend from weld 22 into and embedded within second end portion 20 on opposing second side 40 of line of securement L embedded within second end portion 20 positioned closer to first surface 52 of second end portion 20 than to opposing second surface 54 of second end portion 20.

In further referring to FIG. 5, second plurality 56 of reinforcing fibers 30 wherein adjacent fibers 30 within second plurality 56 of reinforcing fibers 30 extend spaced apart from one another. The second plurality 56 of reinforcing fibers 30 are embedded within first end portion 18 on first side 38 of line of securement L and extend through first end portion 18 positioned closer to opposing second surface 46 of first end portion 18 than to first surface 44 of first end portion 18. Second plurality 56 of reinforcing fibers 30 extend from first end portion 18 into and embedded within weld 22 positioned closer to opposing second surface 50 of weld 22 than to first surface 48 of weld 22. The second plurality 56 of reinforcing fibers 30 extend from weld 22 into and embedded within second end portion 20 on opposing second side 40 of line of securement L embedded within second end portion 20 positioned closer to opposing second surface 54 of the metallic skin structure than to first surface 52 of second end portion 20 of the metallic skin structure.

As mentioned earlier diameters of fibers 30 are in a range of fifty ten thousandths of an inch to and sixty ten thousandths of an inch (0.0050-0.0060 inches). Fibers 30 can be constructed from one of a number of materials such as aramid, ceramic or silicon carbide fibers which are stronger than the aluminum or similar metals used in the construction of metallic skin structures. Reinforcing fibers in this example are embedded within first end portion 18, second end portion 20 and weld 22 a depth of at least one thousandth of an inch (0.001 inch).

In referring to FIGS. 6-9, second example of joint 16′ metallic skin structure is shown. First end portion 18 and second end portion 20 are positioned in an overlying relationship with one another and are secured together along a line of securement L′. First and second end portions 18, 20 are secured together along a line of securement L′, in this example, with rows of fasteners (fasteners not shown in FIG. 6) that extend through bores which extend through both first and second end portions 18, 20. Additionally, joint 16′ includes at least one reinforcing fiber 30, examples of some of fibers 30 are shown in FIG. 6, embedded within at least one of first end portion 18 or second end portion 20 and extends orthogonal relative to line of securement L′.

In referring to FIG. 6 joint 16′ of the metallic skin structure includes first end portion 18 and second end portion 20 positioned, as mentioned above, in overlying relationship with one another. First plurality of bores 58 is positioned in first row 60 within first end portion 18 with adjacent bores in the first plurality of bores 58 spaced apart. Second plurality of bores 62 is positioned in second row 64 within second end portion 20 with adjacent bores in second plurality of bores 62 spaced apart. First row 60 of first plurality of bores 58 align with second row 64 of second plurality of bores 62. This arrangement is similarly reproduced for the other rows 66, 68 of bores shown in first end portion 18 and rows 70, 72 (not completely shown) in second end portion 20.

In referring to FIG. 6, first bore 74 in first plurality of bores 58 is aligned with first bore 76 of second plurality of bores 62 such that first bore 74 of first plurality of bores 58 and first bore 76 of second plurality of bores 62 have a first common central axis 78 such that first fastener 24 may, as seen in FIGS. 8A and 8B, extend through first bore 74 of first plurality of bores 58 and through first bore 76 of second plurality of bores 62. Second bore 80 adjacent to first bore 74 of first plurality of bores 58 is aligned with second bore 82 adjacent to the first bore 76 of second plurality of bores 62 such that second bore 80 of first plurality of bores 58 and second bore 82 of second plurality of bores 62 have second common central axis 84 such that second fastener (not shown) may extend through second bore 80 of first plurality of bores 58 and through second bore 82 of second plurality of bores 62. Line of securement L′ extends between first common central axis 78 and second common central axis 84 extends along joint 16′ as shown as a dashed line.

In referring to FIGS. 7, 8A and 8B first fastener or rivet 24, in this example, is positioned to extend through first bore 74 of first plurality of bores 58 and through first bore 76 of second plurality of bores 62 In FIGS. 8A and 8B. Second fastener (not shown) includes a fastener or rivet (not shown) is positioned to extend through second bore 80 of first plurality of bores 58 and through second bore 82 of second plurality of bores 62. Securement of first end portion 18 and second end portion 20 is completed with securing fasteners such as rivets 24 with positioning them to extend through aligned bores in first and second end portions 18, 20.

In referring to FIG. 9, joint 16′ for the metallic skin structure is shown without fasteners or rivets 24, as seen for example in FIGS. 8A and 8B, securing first end and second end portions 18, 20 together. Joint 16′ includes at least one reinforcing fiber 30 which includes third plurality 86 of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within third plurality 86 of reinforcing fibers 30 extend spaced apart from one another embedded within first end portion 18 of the metallic skin structure. Third plurality 86 of reinforcing fibers 30 extend through first end portion 18 positioned closer to first surface 88 of first end portion 18 than to opposing second surface 90 of first end portion 18. First portion 92 of third plurality 86 of reinforcing fibers 30 extends between first and second adjacent bores 74, 80 as seen in FIG. 9, wherein bores 74 and 80 are of first plurality of bores 58 within first end portion 18 and first portion 92 of third plurality 86 of reinforcing fibers 30 extend from first side 38 of line of securement L′ to opposing second side 40 of line of securement L′ as seen in FIG. 6.

In referring to FIG. 9, joint 16′ includes at least one reinforcing fiber 30 which fourth plurality 94 of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within fourth plurality 94 of reinforcing fibers 30 extend spaced apart from one another embedded within first end portion 18. Fourth plurality 94 of reinforcing fibers 30 extend through first end portion 18 positioned closer to opposing second surface 90 of first end portion 18 than to first surface 88 of first end portion 18. First portion 96 of fourth plurality 94 of reinforcing fibers 30 extend between first and second adjacent bores 74, 80 as seen in FIG. 9, wherein bores 74 and 80 are of first plurality of bores 58 within first end portion 18 and first portion 96 of fourth plurality 94 of reinforcing fibers 30 extends from first side 38 of line of securement L′ to opposing second side 40 of line of securement L′ as seen in FIG. 6.

In referring to FIG. 9, joint 16′ for the metallic skin structure is shown without fasteners or rivets 24, as seen for example in FIGS. 8A and 8B, securing first end and second end portions 18, 20 together. Joint 16′ includes at least one reinforcing fiber 30 which includes fifth plurality 98 of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within fifth plurality 98 of reinforcing fibers 30 extend spaced apart from one another embedded within second end portion 20 of the metallic skin structure. Fifth plurality 98 of reinforcing fibers 30 extends through second end portion 20 positioned closer to first surface 100 of second end portion 20 than to opposing second surface 102 of second end portion 20. First portion 104 of fifth plurality 98 of reinforcing fibers 30 extends between first and second adjacent bores 76, 82 as seen in FIG. 9, wherein bores 76 and 82 are of first plurality of bores 62 within second end portion 20 and first portion 104 of fifth plurality 98 of reinforcing fibers 30 extends from opposing second side 40 of line of securement L′ to first side 38 of line of securement L′ as seen in FIG. 6.

In referring to FIG. 9, joint 16′includes at least one reinforcing fiber 30 which includes sixth plurality of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within sixth plurality 106 of reinforcing fibers 30 extend spaced apart from one another embedded within second end portion 20 of the metallic skin structure. Sixth plurality 106 of reinforcing fibers 30 extends through second end portion 20 positioned closer to opposing second surface 102 of second end portion 20 than to first surface 100 of second end portion 20. First portion 105 of sixth plurality 106 of reinforcing fibers 30 extends between first and second adjacent bores 76, 82 as seen in FIG. 9, wherein bores 76 and 82 are in first plurality of bores 62 within second end portion 20 and first portion 105 of sixth plurality 106 of reinforcing fibers 30 extends from opposing second side 40 of line of securement L′ to first side 38 of line of securement L′ as seen in FIG. 6.

The above described configuration of reinforcing fibers 30, as seen in FIG. 9, are used in both first and second end portions 18, 20 with respect to bores positioned in rows 60, 64, 66, 68, 70 and 72 as seen in FIG. 6.

In referring to FIG. 10, method 108 for fabricating a joint for a metallic skin structure includes step 110 of securing first end portion 18 of the metallic skin structure to second end portion 20 of the metallic skin structure along a line of securement L as seen in the first example of joint 16 discussed above and line of securement L′ as seen in the second example of joint 16′ discussed above as well. Method 108 further includes step 112 of positioning at least one reinforcing fiber 30 embedded within at least one of first end portion 18 or second end portion 20, wherein at least one reinforcing fiber 30 extends orthogonal to line of securement L in the first example and line of securement L′ in the second example.

Step 110 of securing with respect to the first example of joint 16, as seen in FIGS. 4 and 5, includes positioning first end 34 of first end portion 18 and second end 36 of second end portion 20 aligned and facing each other. Step 110 of securing further includes welding first end 34 and second end 36 together, wherein weld 22 defines line of securement L.

In first example of joint 16, at least one reinforcing fiber 30 which includes first plurality 42 of reinforcing fibers 30 wherein adjacent reinforcing fibers 30 within first plurality 42 of reinforcing fibers 30 extend spaced apart from one another. Step 112 of positioning further includes embedding first plurality 42 of reinforcing fibers 30 within first end portion 18 and extending first plurality of reinforcing fibers 30 through first end portion 18 positioned closer to first surface 44 of first end portion 18 than to opposing second surface 46 of first end portion 18. Step 112 of positioning further includes positioning first plurality 42 of reinforcing fibers 30 to extend from first end portion 18 into and embedded within weld 22 positioned closer to first surface 48 of weld 22 than to opposing second surface 50 of weld 22. Further, step 112 of positioning includes positioning first plurality 42 of reinforcing fibers 30 to extend from weld 22 into and embedded within second end portion 20 on an opposing second side 40 of line of securement L and embedded within second end portion 20 positioned closer to first surface 52 of second end portion 20 than to opposing second surface 54 of second end portion 20.

The at least one reinforcing fiber 30 which further includes second plurality 56 of reinforcing fibers 30 wherein adjacent fibers 30 within second plurality 56 of reinforcing fibers 30 extend spaced apart from one another. Step 112 of positioning further includes embedding second plurality 56 of reinforcing fibers 30 within first end portion 18 on a first side 38 of line of securement L and to extend through first end portion 18 positioned closer to opposing second surface 46 of first end portion 18 than to first surface 44 of first end portion 18. Step 112 of positioning further includes positioning second plurality 56 of reinforcing fibers 30 to extend from first end portion 18 of the metallic skin structure into and embedded within weld 22 positioned closer to opposing second surface 50 of weld 22 than to first surface 48 weld 22. Further, step 112 of positioning further includes positioning second plurality 56 of reinforcing fibers 30 to extend from weld 22 into second end portion 20 on opposing second side 40 of line of securement L and embedded within second end portion 20 positioned closer to opposing second surface 54 of the metallic skin structure second end portion than to 52 first surface of second end portion 20.

Method 108 for fabricating second example of joint 16′, as seen in FIGS. 6-9, includes step 112 of positioning at least one reinforcing fiber 30 includes embedding third plurality 86 of reinforcing fibers 30 into first end portion 18, wherein adjacent reinforcing fibers 30 within third plurality 86 of reinforcing fibers 30 extend spaced apart from one another and extend through first end portion 18 positioned closer to first surface 88 of first end portion 18 than to opposing second surface 90 of first end portion 18. Step 112 of positioning at least one reinforcing fiber 30 further includes embedding fourth plurality 94 of reinforcing fibers 30 into first end portion 18, wherein adjacent reinforcing fibers 30 within fourth plurality 94 of reinforcing fibers 30 extend spaced apart from one another and extend through first end portion 18 positioned closer to opposing second surface 90 of first end portion 18 than to first surface 88 of first end portion 18. Step 112 of positioning the at least one reinforcing fiber 30 further includes embedding fifth plurality 98 of reinforcing fibers 30 into second end portion 20, wherein adjacent fibers 30 within fifth plurality 98 of reinforcing fibers 30 extend spaced apart from one another and extend through second end portion 20 positioned closer to first surface 100 of second end portion 20 than to opposing second surface 102 of second end portion 20. Step 112 of positioning the at least one reinforcing fiber 30 further includes embedding sixth plurality 106 of reinforcing fibers 30 into second end portion 20, wherein adjacent reinforcing fibers 30 within sixth plurality 106 of reinforcing fibers 30 extend spaced apart from one another and extend through second end portion 20 positioned closer to opposing second surface 102 of second end portion 20 than to first surface 100 of second end portion 20. Step 110 of securing first end portion 18 to second end portion 20 includes positioning first end portion 18 and second end portion 20 in an overlying relationship with one another.

Step 110 of securing, in method 108, further includes positioning first plurality of bores 58 in first row 60 within first end portion 18 of the metallic skin structure with adjacent bores, such as first bore 74 and second bore 80 in first plurality of bores 58, are spaced apart. Step 110 of securing further includes positioning second plurality of bores 62 in second row 64 within second end portion 20 of the metallic skin structure with adjacent bores, such as first bore 76 and second bore 82, in second plurality of bores 62, are spaced apart such that first row 60 of first plurality of bores 58 aligns with second row 64 of second plurality of bores 62.

Step 110 of securing further includes a step of positioning first bore 74 of first plurality of bores 58 in alignment with first bore 76 of second plurality of bores 62 such that first bore 76 of first plurality of bores 58 and first bore 76 of second plurality of bores 62 have a first common central axis 78 and positioning a first fastener, such as rivet 24, to extend through first bore 74 of first plurality of bores 58 and through first bore 76 of second plurality of bores 62. Step 110 of securing further includes a step of positioning second bore 80 adjacent to first bore 74 of first plurality of bores 58 in alignment with second bore 82 adjacent to first bore 76 of second plurality of bores 62 such that second bore 80 of first plurality of bores 58 and second bore 82 of second plurality of bores 62 have a second common central axis 84 and positioning a second fastener (not shown), such as rivet 24, to extend through second bore 80 of first plurality of bores 58 and through second bore 82 of second plurality of bores 62 and line of securement L′ extends between first common central axis 78 and second common central axis 84. Line of securement L′ can extend in either direction along line of securement L′. As mentioned above, the step of securing further includes the first fastener comprises rivet 24 and the second fastener (not shown) comprises a rivet as seen for example in FIGS. 8A and 8B.

In referring to FIGS. 6 and 9, step 110 of securing further includes positioning first bore 74 and second bore 80, of first plurality of bores 58 within first end portion 18, resulting in: first portion 92 of third plurality 86 of reinforcing fibers 30 extending within first end portion 18 between first and second adjacent bores 74, 80 of first plurality of bores 58 and extending from first side 38 of line of securement L′ to the opposing second side 40 of line of securement L′ and first portion 96 of fourth plurality 94 of reinforcing fibers 30 extending within first end portion 18 between first and second adjacent bores 74, 80 of first plurality of bores 58 and extending from first side 38 of line of securement L′ to opposing second side 40 of line of securement L′. Step 110 of securing further includes positioning first bore 76 and the second bore 82 in second plurality of bores 62 positioned within second end portion 20, resulting in: first portion 104 of fifth plurality 98 of reinforcing fibers 30 extending within second end portion 20 between first and second adjacent bores 76, 82 in second plurality of bores 62 and extending from opposing second side 40 of line of securement L′ to first side 38 of line of securement L′; and first portion 105 of sixth plurality 106 of reinforcing fibers 30 extending within second end portion 20 between first and second adjacent bores 76, 82 of second plurality of bores 62 and extending from opposing second side 40 of line of securement L′ to first side 38 of line of securement L′.

Step 110 of securing further includes positioning first bore 74 of first plurality of bores 58 positioned within first end portion 18, further resulting in second portion 114 of third plurality 86 of reinforcing fibers 30 is cut into a first section 116 and second section 118. Cut second portion 114 of third plurality 86 of reinforcing fibers 30 can be seen on opposing sides of first bore 74 having termination ends 86′ at perimeter P of first bore 74 in FIG. 8A and 8B. First section 116 extends within first side 38 of line of securement L′ and terminates at perimeter P of first bore 74 positioned in first side 38 of line of securement L′ having termination ends 86′ as seen in FIG. 8A. Second section 118 extends from perimeter P of first bore 74 positioned within opposing second side 40 of line of securement L′ and extends away from first bore 74. Termination ends 86′ as seen in FIG. 8B is where second section 118 of second portion 114 of third plurality 86 reinforcing fibers commence in extending away from first bore 74.

Second portion 120 of fourth plurality 94 of reinforcing fibers 30 wherein each reinforcing fiber 30 of second portion 120 of fourth plurality 94 of reinforcing fibers 30 is cut into a first section (not shown) and a second section (not shown) however underlie first section 116 and second section 118 respectively of third plurality of reinforcing fibers 86. Cut fourth plurality 94 of reinforcing fibers 30 can be seen on opposing sides of first bore 74 having termination ends 94′at perimeter P of first bore 74 in FIGS. 8A and 8B. As similarly described for third plurality 86 of reinforcing fibers 30 above, the first section (not shown) extends within first side 38 of line of securement L′ and terminates at perimeter P as seen as termination ends 94′ in FIGS. 8A of first bore 74 positioned in first side 38 of line of securement L′. The second section (not shown) extends from perimeter P of first bore 74 from termination ends 94′ seen in FIG. 8B. Second section (not shown) is positioned within opposing second side 40 of line of securement L′ and extends away from first bore 74.

Step 110 of securing further includes positioning first bore 76 of second plurality of bores 62 positioned within second end portion 20, further resulting in second portion 122 of fifth plurality 98 of reinforcing fibers 30 each being cut into a first section 124 and second section 126. Cut second portion 122 of fifth plurality 98 of reinforcing fibers 30 can be seen on opposing sides of first bore 76 having termination ends 98′at perimeter P of first bore 76 in FIGS. 8A and 8B. First section 124 extends within first side 38 of line of securement L′ and terminates at perimeter P of first bore 76 positioned in opposing second side 40 of line of securement L′ having termination ends 98′ as seen in FIG. 8A. Second section 126 extends from perimeter P of first bore 76 positioned within opposing second side 40 of line of securement L′ and extends away from first bore 76. Termination ends 98′ as seen in FIG. 8B is where second section 126 of second portion 122 of fifth plurality 98 of reinforcing fibers 30 commence in extending away from first bore 76. Second portion 128 of sixth plurality 106 of reinforcing fibers 30 wherein each reinforcing fiber 30 of second portion 128 of sixth plurality 106 of reinforcing fibers 30 is cut into a first section (not shown) and a second section (not shown) however underlie first section 124 and second section 126 respectively of fifth plurality 98 of reinforcing fibers 30. Cut sixth plurality 106 of reinforcing fibers 30 can be seen on opposing sides of first bore 76 having termination ends 106′ at perimeter P of first bore 76 in FIGS. 8A and 8B. As similarly described for fifth plurality 98 of reinforcing fibers 30 above, the first section (not shown) extends within first side 38 of line of securement L′ and terminates at perimeter P as seen as termination ends 106′ in FIG. 8A of first bore 76 positioned in first side 38 of line of securement L′. The second section (not shown) extends from perimeter P of first bore 76 from termination ends 106′ seen in FIG. 8B. Second section (not shown) is positioned within opposing second side 40 of line of securement L′ and extends away from first bore 76.

While various embodiments have been described above, this disclosure is not intended to be limited thereto. Variations can be made to the disclosed embodiments that are still within the scope of the appended claims. 

What is claimed:
 1. A joint for a metallic skin structure, comprising: a first end portion of the metallic skin structure; a second end portion of the metallic skin structure, wherein the first end portion and the second end portion of the metallic skin structure are secured together along a line of securement; and at least one reinforcing fiber embedded within at least one of the first end portion of the metallic skin structure or the second end portion of the metallic skin structure extends orthogonal relative to the line of securement.
 2. The joint for the metallic skin structure of claim 1, wherein: the first end portion includes a first end and the second end portion includes a second end; the first and second ends are positioned aligned and facing each other; the first end and second end are secured together with a weld positioned between the first end and the second end; and the weld extends along the first end and second end and defines the line of securement.
 3. The joint for the metallic skin structure of claim 2, wherein: the at least one reinforcing fiber is embedded within the first end portion positioned on a first side of the line of securement; the at least one reinforcing fiber extends from the first end portion into and embedded within the weld; and the at least one reinforcing fiber extends from the weld into and embedded within the second end portion positioned on an opposing second side of the line of securement.
 4. The joint for the metallic skin structure of claim 3, wherein: the at least one reinforcing fiber includes a first plurality of reinforcing fibers wherein adjacent reinforcing fibers within the first plurality of reinforcing fibers extend spaced apart from one another; the first plurality of reinforcing fibers are embedded within the first end portion on the first side of the line of securement and extend through the first end portion positioned closer to a first surface of the first end portion than to an opposing second surface of the first end portion; the first plurality of reinforcing fibers extend from the first end portion into and embedded within the weld positioned closer to a first surface of the weld than to an opposing second surface of the weld; and the first plurality of reinforcing fibers extend from the weld into and embedded within the second end portion on the opposing second side of the line of securement and embedded within the second end portion positioned closer to a first surface of the second end portion than to an opposing second surface of the second end portion.
 5. The joint for the metallic skin structure of claim 4, further includes: a second plurality of reinforcing fibers wherein adjacent fibers within the second plurality of reinforcing fibers extend spaced apart from one another; the second plurality of reinforcing fibers are embedded within the first end portion on the first side of the line of securement and extend through the first end portion positioned closer to the opposing second surface of the first end portion than to the first surface of the first end portion; the second plurality of reinforcing fibers extend from the first end portion into and embedded within the weld positioned closer to the opposing second surface of the weld than to the first surface of the weld; and the second plurality of reinforcing fibers extend from the weld into and embedded within the second end portion on the opposing second side of the line of securement and embedded within the second end portion positioned closer to the opposing second surface than to the first surface of the second end portion.
 6. The joint for the metallic skin structure of claim 1, wherein: a diameter of the at least one reinforcing fiber is in a range of fifty ten thousandths of an inch (0.0050 inch) to sixty ten thousandths of an inch (0.0060 inch); the at least one reinforcing fiber comprises one of aramid, ceramic or silicon carbide; and the at least one reinforcing fiber is embedded within the at least one of the first end portion or the second end portion a depth distance of at least one thousandth of an inch (0.001 inch).
 7. The joint for the metallic skin structure of claim 1, wherein: the first end portion and the second end portion are positioned in an overlying relationship with one another; a first plurality of bores is positioned in a first row within the first end portion with adjacent bores in the first plurality of bores spaced apart; a second plurality of bores is positioned in a second row within the second end portion with adjacent bores in the second plurality of bores spaced apart; and the first row of the first plurality of bores align with the second row of the second plurality of bores.
 8. The joint for the metallic skin structure of claim 7, wherein: a first bore in the first plurality of bores is aligned with a first bore of the second plurality of bores such that the first bore of the first plurality of bores and the first bore of the second plurality of bores have a first common central axis such that a first fastener may extend through the first bore of the first plurality of bores and through the first bore of the second plurality of bores; a second bore adjacent to the first bore of the first plurality of bores is aligned with a second bore adjacent to the first bore of the second plurality of bores such that the second bore of the first plurality of bores and the second bore of the second plurality of bores have a second common central axis such that a second fastener may extend through the second bore of the first plurality of bores and through the second bore of the second plurality of bores; and the line of securement extends between the first common central axis and the second common central axis.
 9. The joint for the metallic skin structure of claim 8, further includes: a first fastener comprising a rivet positioned to extend through the first bore of the first plurality of bores and through the first bore of the second plurality of bores; and a second fastener comprising a rivet positioned to extend through the second bore of the first plurality of bores and through the second bore of the second plurality of bores.
 10. The joint for the metallic skin structure of claim 8, wherein: the at least one reinforcing fiber comprises a third plurality of reinforcing fibers wherein adjacent reinforcing fibers within the third plurality of reinforcing fibers extend spaced apart from one another embedded within the first end portion, wherein: the third plurality of reinforcing fibers extends through the first end portion positioned closer to a first surface of the first end portion than to an opposing second surface of the first end portion; and a first portion of the third plurality of reinforcing fibers extends between the first and second adjacent bores of the first plurality of bores within the first end portion and the first portion of the third plurality of reinforcing fibers extends from a first side of the line of securement to an opposing second side of the line of securement; and the at least one reinforcing fiber comprises a fourth plurality of reinforcing fibers wherein adjacent reinforcing fibers within the fourth plurality of reinforcing fibers extend spaced apart from one another embedded within the first end portion, wherein: the fourth plurality of reinforcing fibers extends through the first end portion positioned closer to the opposing second surface of the first end portion than to the first surface of the first end portion; and a first portion of the fourth plurality of reinforcing fibers extends between the first and second adjacent bores of the first plurality of bores within the first end portion and the first portion of the fourth plurality of reinforcing fibers extends from the first side of the line of securement to the opposing second side of the line of securement.
 11. The joint for the metallic skin structure of claim 10, wherein: the at least one reinforcing fiber comprises a fifth plurality of reinforcing fibers wherein adjacent reinforcing fibers within the fifth plurality of reinforcing fibers extend spaced apart from one another embedded within the second end portion, wherein: the fifth plurality of reinforcing fibers extends through the second end portion positioned closer to a first surface of the second end portion than to an opposing second surface of the second end portion; and a first portion of the fifth plurality of reinforcing fibers extends between the first and second adjacent bores of the second plurality of bores within the second end portion and the first portion of the fifth plurality of reinforcing fibers extends from the opposing second side of the line of securement to the first side of the line of securement; and the at least one reinforcing fiber comprises a sixth plurality of reinforcing fibers wherein adjacent reinforcing fibers within the sixth plurality of reinforcing fibers extend spaced apart from one another embedded within the second end portion, wherein: the sixth plurality of reinforcing fibers extends through the second end portion positioned closer to the opposing second surface of the second end portion than to the first surface of the second end portion; and a first portion of the sixth plurality of reinforcing fibers extends between the first and second adjacent bores of the second plurality of bores within the second end portion and the first portion of the sixth plurality of reinforcing fibers extends from the opposing second side of the line of securement to the first side of the line of securement.
 12. A method for fabricating a joint for a metallic skin structure, comprising the steps of: securing a first end portion of the metallic skin structure to a second end portion of the metallic skin structure along a line of securement; and positioning at least one reinforcing fiber embedded within at least one of the first end portion or the second end portion, wherein the at least one reinforcing fiber extends orthogonal to the line of securement.
 13. The method for fabricating, of claim 12, wherein: the step of securing further includes positioning a first end of the first end portion and a second end of the second end portion aligned and facing each other; and the step of securing further includes welding the first end and the second end together, wherein the weld defines the line of securement.
 14. The method for fabricating, of claim 13, wherein: the at least one reinforcing fiber further includes a first plurality of reinforcing fibers wherein adjacent reinforcing fibers within the first plurality of reinforcing fibers extend spaced apart from one another; the step of positioning further includes embedding the first plurality of reinforcing fibers within the first end portion and extending the first plurality of reinforcing fibers through the first end portion positioned closer to a first surface of the first end portion than to an opposing second surface of the first end portion; the step of positioning further includes positioning the first plurality of reinforcing fibers to extend from the first end portion into and embedded within the weld positioned closer to a first surface of the weld than to an opposing second surface of the weld; and the step of positioning further includes positioning the first plurality of reinforcing fibers to extend from the weld into and embedded within the second end portion on an opposing second side of the line of securement and embedded within the second end portion positioned closer to a first surface of the second end portion than to an opposing second surface of the second end portion.
 15. The method for fabricating, of claim 14, wherein: the at least one reinforcing fiber further includes a second plurality of reinforcing fibers wherein adjacent fibers within the second plurality of reinforcing fibers extend spaced apart from one another; the step of positioning further includes embedding the second plurality of reinforcing fibers within the first end portion on a first side of the line of securement and to extend through the first end portion positioned closer to the opposing second surface of the first end portion than to the first surface of the first end portion; the step of positioning further includes positioning the second plurality of reinforcing fibers to extend from the first end portion into and embedded within the weld positioned closer to the opposing second surface of the weld than to the first surface of the weld; and the step of positioning further includes positioning the second plurality of reinforcing fibers to extend from the weld into and embedded within the second end portion on the opposing second side of the line of securement and embedded within the second end portion positioned closer to the opposing second surface of the second end portion than to the first surface of the second end portion.
 16. The method for fabricating, of claim 12, wherein: the step of positioning at least one reinforcing fiber includes embedding a third plurality of reinforcing fibers into the first end portion, wherein adjacent reinforcing fibers within the third plurality of reinforcing fibers extend spaced apart from one another and extend through the first end portion positioned closer to a first surface of the first end portion than to an opposing second surface of the first end portion; the step of positioning the at least one reinforcing fiber further includes embedding a fourth plurality of reinforcing fibers into the first end portion, wherein adjacent reinforcing fibers within the fourth plurality of reinforcing fibers extend spaced apart from one another and extend through the first end portion positioned closer to the opposing second surface of the first end portion than to the first surface of the first end portion; the step of positioning the at least one reinforcing fiber further includes embedding a fifth plurality of reinforcing fibers into the second end portion, wherein adjacent fibers within the fifth plurality of reinforcing fibers extend spaced apart from one another and extend through the second end portion positioned closer to a first surface of the second end portion than to an opposing second surface of the second end portion; the step of positioning the at least one reinforcing fiber further includes embedding a sixth plurality of reinforcing fibers into the second end portion, wherein adjacent reinforcing fibers within the sixth plurality of reinforcing fibers extend spaced apart from one another and extend through the second end portion positioned closer to the opposing second surface of the second end portion than to the first surface of the second end portion; and the step of securing a first end portion of the metallic skin structure to a second end portion of the metallic skin structure includes positioning the first end portion and the second end portion in an overlying relationship with one another.
 17. The method for fabricating, of claim 16, wherein: the step of securing further includes positioning a first plurality of bores in a first row within the first end portion with adjacent bores in the first plurality of bores spaced apart; and the step of securing further includes positioning a second plurality of bores in a second row within the second end portion with adjacent bores in the second plurality of bores spaced apart such that the first row of the first plurality of bores aligns with the second row of the second plurality of bores.
 18. The method for fabricating, of claim 17, wherein: the step of securing further includes a step of positioning a first bore of the first plurality of bores in alignment with a first bore of the second plurality of bores such that the first bore of the first plurality of bores and the first bore of the second plurality of bores have a first common central axis and positioning a first fastener to extend through the first bore of the first plurality of bores and through the first bore of the second plurality of bores; and the step of securing further includes a step of positioning a second bore adjacent to the first bore of the first plurality of bores in alignment with a second bore adjacent to the first bore of the second plurality of bores such that the second bore of the first plurality of bores and the second bore of the second plurality of bores have a second common central axis and positioning a second fastener to extend through the second bore of the first plurality of bores and through the second bore of the second plurality of bores wherein the line of securement extends between the first common central axis and the second common central axis.
 19. The method for fabricating, of claim 18, wherein the first fastener comprises a rivet and the second fastener comprises a rivet.
 20. The method for fabricating, of claim 18, wherein: the step of securing further includes positioning the first bore and the second bore of the first plurality of bores within the first end portion, resulting in: a first portion of the third plurality of reinforcing fibers extending within the first end portion between the first and second adjacent bores of the first plurality of bores and extending from a first side of the line of securement to an opposing second side of the line of securement; and a first portion of the fourth plurality of reinforcing fibers extending within the first end portion between the first and second adjacent bores of the first plurality of bores and extending from the first side of the line of securement to the opposing second side of the line of securement; and the step of securing further includes positioning the first bore and the second bore in the second plurality of bores positioned within the second end portion, resulting in: a first portion of the fifth plurality of reinforcing fibers extending within the second end portion between the first and second adjacent bores in the second plurality of bores and extending from the opposing second side of the line of securement to the first side of the line of securement; and a first portion of the sixth plurality of reinforcing fibers extending within the second end portion between the first and second adjacent bores of the second plurality of bores and extending from the opposing second side of the line of securement to the first side of the line of securement.
 21. The method for fabricating, of claim 20, wherein: the step of securing further includes positioning the first bore of the first plurality of bores within the first end portion, further resulting in: a second portion of the third plurality of reinforcing fibers is cut into a first section and a second section, wherein: the first section extends within the first side of the line of securement and terminates at a perimeter of the first bore of the first plurality of bores positioned in the first side of the line of securement; and the second section extends from the perimeter of the first bore of the first plurality of bores positioned within the opposing second side of the line of securement and extends away from the first bore; and a second portion of the fourth plurality of reinforcing fibers is cut into a first section and a second section, wherein: the first section extends within the first side of the line of securement and terminates at a perimeter of the first bore of the first plurality of bores positioned in the first side of the line of securement; and the second section extends from the perimeter of the first bore of the first plurality of bores positioned within the opposing second side of the line of securement and extends away from the first bore of the first plurality of bores.
 22. The method for fabricating, of claim 20, wherein: the step of securing further includes positioning the first bore of the second plurality of bores in the second end portion, further resulting in: a second portion of the fifth plurality of reinforcing fibers wherein: each reinforcing fiber of the second portion of the fifth plurality of reinforcing fibers is cut into a first section and a second section; the first section extends within the opposing second side of the line of securement and terminates at a perimeter of the first bore of the second plurality of bores positioned in the opposing second side of the line of securement; and the second section extends from the perimeter of the first bore of the second plurality of bores positioned within the first side of the line of securement and extends away from the first bore of the second plurality of bores; and a second portion of the sixth plurality of reinforcing fibers wherein: each reinforcing fiber of the second portion of the sixth plurality of reinforcing fibers is cut into a first section and a second section; the first section extends within the opposing second side of the line of securement and terminates at a perimeter of the first bore of the second plurality of bores positioned in the opposing second side of the line of securement; and the second section extends from the perimeter of the first bore of the second plurality of bores positioned within the first side of the line of securement and extends away from the first bore of the second plurality of bores. 